“…According to Fujiya (1970) and Ventilla (1984), the survival rate of the hardened oysters in Hiroshima waters was 70-90%, while the rate was only 20% with no hardening. After 6-8 months of grow-out, the hardened oysters reach over 80 mm in shell length and 5-6 g in tissue wet weight (Kang et al, 2000(Kang et al, , 2010Hyun et al, 2001). However, quantity of the harvested spats fluctuates year to year in an unpredictable manner (Park et al, 1999a;Jeong et al, 2001;Min et al, 2004).…”